Depolarizing compound



UNITED STATES PATENT OFFICE.

AUGUST Wl PARTZ, OF PHILADELPHIA, PENNSYLVANIA.

DEPOLARIZING COMPOUND.

SPECIFICATION forming part of Letters Patent No. 379,180, dated. March 6, 1888.

Application filed October 6, 1896v Serial No. 215,481.

product proved to be much less effective depolariz'ers than similar solutions made directly of the same ingredients, and this I found to be chiefly owing to an abundant and unavoidable escape of oxygeni. 6., reduction of chromic acid to oxide through the heat required for expelling the water toward the end of the operation.

In order to obtain a solid compound without evaporation, and the consequent great loss of oxygen, other chemists managed to dispense with the use of water by heating a mixture of sulphuric acid and sulphate of potash'till the salt was dissolved andthen adding bichromate of potash. Though this process may be so conducted that the formation of chromic oxide is less considerable than by the process above re-- ferred to, this advantage is gained by the in-, troduction of a substance which increases the bulk and cost of the product without adding to its efficiency as a depolarizer.

The object of my invention is to produce a solid compound consisting of chromic acid, sulphuric acid, and so much acid sulphate of potash as will result from the action of sulphuric acid upon bichromate of potash, and being virtually free from chromic oxide. I

The success of the'process here involved degrams of bichromate of potash in a powdery state,and to prevent the forming of crusty ag- (No specimens.)

glomcrations I let the bichromate fall through a screen upon the acid while stirring it in. The intended chemical change takes place with disengagement of heat. As the pulveri-zing of bichromate of potash and its subsequent handling is a matter of muchiuconvcnience on account of the injurious effect of the dust upon the mucous membranes, I have contrived to avoid the mechanical reduction of the salt and to procure a less dusty material by heating commercial bichromate in an iron vessel just enough to bring it into fusion and then pouring it upon metallic trays or plates,where it forms into crystals which break up into a gritty powder while cooling.

The incorporation of the stated quantities of sulphuric acid and bichromate should be completed in rather less than fifteen minutes, as a continuation of the process after the mass has become well heated by chemical action is apt to cause an emission of oxygen. When the mass has cooled down to a semi-fluid state, it may be cast into molds of suitable material, or it may be left in theporcelain dish and broken up into granular lumps while solidifying. The red amorpho-crystalline product thus obtained consists of chemically-combined chromic and sulphuric acid and of the acid sulphate of potash due to the conversion of the bichromate salt by a portion of the sulphuric acid without-containing any appreciable intermixture of chromic oxide.

The product being hygroscopic must be kept in well-closed vessels or in air-tight envelopes of a pliable material which it does not act upon. If it is cast in bars or cakes, I wrap them in paraffined paper or cloth and then dip the parcels into molten paraffine, thus putting the article at a low cost into a suitable commercial form.

When the compound is to be used for a Poggendorff or a Grenet battery, one pound of it may be dissolved in from two and one-half to live pints of water, according to the desired strength of the liquid. When employed in my acid-gravity battery, it is put undissolvcd into the glass tubes with which the apparatus is provided.

I do not hold myself strictly to the proportions of sulphuric acid and bichromate of pot-' ash above stated, as they may be varied to some extent without the nature of the com- I iziug compound,which consists in decompospound being thereby materially changed, nor do I confine myself strictly to the mode of operating above set forth.

By the expression without the application of heat, as herein employed, is meant without the application of heat from an external source; or, in other words, without the employment of heat other than that generated by the chemical reactions between the substances employed.

Having thus described my invention,what I claim is 1. The solid depolarizing compound herein described, consisting of chromic acid, sulphuric acid, and only so much acid sulphate of potash as is due to the action of sulphuric acid upon the bichromate of potash employed, said compound being practically free from chromic oxide.

2. The process of producing a solid depolaring biehromate of potash by sulphuric acid without the aid of water or an alkaline sulphate and without the application of heat.

3. The process of producing a solid depolarizing compound, consisting, first, in reducing the bichroinatc of potash to a powdery state by fusion and cooling, and then decomposing the powdered mass by sulphuric acid.

4:. As a new product, the herein-described solid depolarizing compound resulting from the decomposition of bichromatc of potash by sulphuric acid without the aid of water or an alkaline sulphate or applied heat.

In testimony whereof I hereunto set my hand, this 24th day of September, 1886, in the presence of two attesting witnesses.

AUGUST F. \V. PARTZ.

Witnesses:

C. A. NEALE, ANDREW PARKER. 

